A. Field of the Invention
This invention relates to the fields of telecommunications and wireless Internet Protocol (IP) network routing. More particularly, the invention relates to a process by which a mobile communications device, for example, a laptop computer equipped with a cellular telephone modem, is located and communication between the device and a terminal on an IP network is initiated.
B. Description of Related Art
Wireless communications networks offer much flexibility to the user, in that they allow users of portable communications devices, such as personal digital assistants, laptop computers, telephones, and other appliances to get connected to the public switched telephone network from any location within the region served by the wireless network. Connolly et al., U.S. Pat. No. 5,325,419, discloses a personal communication system by which a user uses an RF link to communicate with an intelligent base station. The intelligent base stations provide radio access along with an Integrated Services Digital Network (ISDN) interface to the public switched telephone network. The PSTN aspect of the system has three components: a personal communications switching center, where telephone central office switches have certain characteristics, a signaling transfer point, and a service control point where an intelligent data base exists maintaining certain user features and records.
The patent application of Yingchun Xu, et al., Ser. No. 08/887,313, assigned to the assignee of the present invention and which is fully incorporated by reference herein, describes a system by which a wireless communications device such as laptop computer with a cellular modem may access a packet-switched (e.g., IP) data network such as a corporate backbone network or the Internet. In the Xu et al. system, a frame relay line connected to the wireless network couples the remote wireless user to the packet-switched network via an all-digital network access server. This type of network access server is occasionally known in the art as an InterWorking Unit (IWU) and the two terms are occasionally used interchangeably herein. The network access server provides an interface to the frame relay line and wireless network and an interface (including router functionality) to the packet switched network. The Xu et al. application further discloses certain accounting and routing techniques that permit network access to authorized users, while at the same time providing convenient authorization and accounting techniques to be performed by the entity operating the network access server. Network access servers suitable for use as a platform for an IWU are, per se, known in the art and commercially available from companies such as 3Com Corporation. They are also described in the patent literature. See, e.g., the patent awarded to Dale M. Walsh et al., U.S. Pat. No. 5,528,595, incorporated by reference herein.
In the prior art, the mobile device typically must dial into the IP network through a network access server or otherwise register with an InterWorking Unit or gateway router/home agent in order to gain access to the IP network and communicate with a remote terminal on the network. If a terminal on the network were to attempt to initiate communication with the mobile device on its own, the terminal on the network and/or other communications elements in the IP network or wireless network would have to know several things: where the mobile terminal is located, whether it was within range of the wireless network, whether it was ready to receive the data (i.e., booted up), and possibly still other pieces of information, such as the information uniquely identifying the device in the wireless network such as its International Mobile Subscriber Identity (IMSI) number and/or its Electronic Serial Number (ESN). Obviously, this circumstance makes it quite cumbersome, if not impossible, for a terminal on the IP network to initiate communication with an unregistered, wireless mobile communications device. For example, if a home agent for the mobile device receives an incoming IP packet for the device but does not have a record of where the device is located (e.g., a mobility binding record indicating where to send the packets received from the terminal), it would simply drop the packets.
The present invention attempts to overcome these problems and provide a simple, efficient and automatic way of finding a mobile user when an IP packet is addressed to them. Once located, the method allows the terminal on the IP network to initiate communication with the mobile wireless communications device. In one possible embodiment, the invention uses the paging ability of the wireless network to locate the wireless mobile communications device whenever a terminal on the IP network attempts to send a packet whose IP destination address matches that of the mobile device. When the mobile device responds to the page it automatically becomes connected to the IP network and is able to communicate with the remote terminal.
A method is provided for finding a mobile wireless communications device when an Internet Protocol (IP) packet from a remote user over an IP network is send to the device. The method comprises the steps of receiving the IP packet at a home agent associated with a wireless communications network. The IP packet includes an IP address assigned to the device. In the present example, the home agent does not have a mobility binding record in order to route the packet to the mobile device. Instead of dropping the packet, the home agent sends an access-request packet to an authentication server containing the IP address of the device. The authentication server maintains a table mapping the IP address for the device to an identification number uniquely associated with said device, such as the device""s IMSI/ESN number. The entries in the table are populated manually (or otherwise) by the provider of the IP network access service for the wireless device.
In the event that the device is authorized to receive the IP packet, e.g., it is a current subscriber to the service and its bills are paid, the authentication server sends an access-accept packet to the home agent. The access-accept packet includes the identification number for the device. In response to the receipt of the access-accept packet, the home agent uses the identification number to alert the device that an incoming IP packet has been received to thereby initiate communication between the device and the remote user. For example, the home agent initiates a page of the device through the wireless network, or uses a signaling system 7 network to locate the device and initiate the page. When the device responds to the page, the device becomes connected via an InterWorking Unit to the IP network and communication between the device and the remote terminal can proceed.
The nature of the wireless mobile communications device is not important. It could be a personal digital assistant device, laptop computer, or any other type of device that is capable of communication over an IP data network with a remote terminal.
In another aspect of the invention, a wireless communication service provider system is described. The system includes a home agent for a plurality of mobile communications devices, a network access server (IWU) connected to the home agent over a local area network, and an authentication server connected to both the home agent and the network access server. The network access server provides access for a mobile communications device to an Internet Protocol (IP) network, such as for example a corporate backbone network or the internet. The authentication server maintains a table mapping Internet Protocol (IP) addresses for the mobile communications devices to identification information uniquely associated with the devices, such as the IMSI/ESN numbers. When the home agent receives an IP packet containing an IP address assigned to the device from a remote user, and does not have a mobility binding record for the device, it responsively sends an access-request packet containing the IP address to the authentication server. The authentication server (e.g., a RADIUS server) responsively sends an access-accept packet to the home agent in the event that the device is authorized to communicate with the remote user. The access-accept packet includes the identification information. The home agent uses the identification information to locate, page and automatically connect the device via the network access server to the IP network and thereby provide communication between the device and the remote user over the IP network.
In yet another aspect of the invention, an authentication server for a wireless communications network is provided. The authentication server is coupled to a home agent receiving an Internet Protocol (IP) packet from a remote user destined for a mobile communications device. The authentication server comprises a memory containing a table mapping an IP address contained in the IP packet to an identification number for the device, and a central processing unit processing an access-request packet containing the IP address from the home agent. The authentication uses the table to determine whether the device is authorized to receive the IP packet. The authentication server further has a software program running on the central processing unit that generates an access-accept packet and issues the access-accept packet to the home agent in the event that the authentication server authenticates the device with the table.